1. Field of the Invention
The invention relates to a method for delineation of an electrocardiogram signal, more particularly to a method for delineation of characteristic points in an electrocardiogram signal, and a storage medium, an electronic device, and an electrocardiogram signal analyzing system for implementing the method.
2. Description of the Related Art
As shown in FIG. 1, an electrocardiogram (ECG) signal 9 can be divided into a P-wave, a Q-wave, an R-wave, a T-wave and a U-wave for every period (Δt) of the electrocardiogram signal 9. In terms of diagnostic and biological significance, the PR interval between the P-wave and the R-wave represents the time during contraction of the atria and the ventricles; the QRS-interval of a QRS-complex between the Q-wave and the S-wave represents the time during transmission of electricity from the AV node to the ventricles for causing the ventricles to contract; and the QT interval between the Q-wave and the T-wave represents the time during recovery of the ventricles after contraction occurs. Therefore, how to accurately and effectively delineate and locate the various wave segments and intervals in an electrocardiogram signal is crucial to making correct diagnoses.
In clinical diagnoses, doctors usually locate the wave intervals in an electrocardiogram signal by naked eye observation based on grids provided on a record graph paper. As technology advances, several delineation methods for electrocardiogram signals have been developed and implemented in computer-executable manners. For instance, Barro et al. developed a diagnostic system based on the method of spectral analysis for detection of severe pathological changes such as ventricular tachycardia and ventricular fibrillation. In the diagnostic system, diseases are indicated by corresponding spectral characteristic distributions of the electrocardiogram signal, and the spectral characteristic distributions are taken as the basis for diagnostic reading of the electrocardiogram signal. Murthy et al. implemented the method of spectral analysis to characterize the P-wave, QRS-complex and T-wave in an electrocardiogram signal based on the spectral differences among the various waves. Woolfsion et al. used the method of zero-crossing to analyze life threatening cardiac arrhythmia, and compared various characteristics of the method of zero-crossing and the method of spectral analysis. Okada et al. used a simple combination of digital filters for the detection of the QRS-complex and for the measurement of the interval of the QRS-complex. Hamilton et al. used digital filtering techniques for quantitative investigation of the QRS-complex detection. Atarius et al. used the method of maximum likelihood for detection of the phenomenon of cardiac late potentials when the heart suffers from myocardial ischemia or myocardial anoxia.
In addition, S. Mallat et al. applied the method of multiscale differential operator (MDO) for edge detection in image processing. However, the applicants are unaware of a teaching in the prior art to apply the method of multiscale differential operator to the delineation of electrocardiogram signals and the categorization of wave segment morphologies.
Although the abovementioned methods are capable of delineating certain wave segments in an electrocardiogram signal, such as the obvious QRS-complex, precise locations of on and off points of each wave segment, especially the T-wave, cannot be determined using the same methods. This is because the T-wave is a more complex wave segment, starts more gradually, and has a lot of varying shapes as compared to the R-wave or other wave segments in an electrocardiogram signal.